Seasonal Dimorphism in Buttcrfiies. 203 



pupa emerged after six days' heating (eight days in pupa); 

 unfortunately it had a difficulty in emerging, and I arrived 

 too late to help it. But such as it is, it seems to me 

 a very interesting specimen, for'it is clearly intermediate 

 in colouring, being therefore a step backwards towards the 

 dry form. Its intermediate character is shown on the 

 underside of hind wings, in the deeper ground-colour and 

 more accentuated white bands, and on the upper side by 

 the broad interruption about radial nervules of the sub- 

 marginal black line in forewings, a character which .only 

 occurs in the dry or intermediate form of the female, and 

 never in the early wet form of that sex." — G. A. K. M. 



The two specimens here mentioned are both in the 

 Hope collection. The difference between them is marked, 

 the one which emerged on Nov. 27, from the pupa which 

 was already seven days old before being exposed to dry 

 warmth, being a wet-season male of the ordinary kind ; 

 while the other, which was only two days old when sub- 

 jected to the same dry warmth, emerging on Nov. 30, is 

 a crippled female, distinctly of the dry-season form, not 

 extreme, but quite unmistakable, and entirely differing from 

 specimens captured in the same locality at the same time 

 of year. 



"Malvern, Natal; Feb. 21, 1897. — I have been trying to 

 find some reason to account for the occurrence of the marked 

 varieties of Bihlia ilithyia. This again is a widespread 

 and common species, and comparatively conspicuous, so 

 that there must be some sort of protective agency at 

 work. I can only explain it by the fact that B. ilithyia 

 strongly suggests an Acrma on the wing. Its general 

 coloration, somewhat elongated wings and flapping flight 

 (so different from that of its congeners), all tend to suggest 

 this. That the typical form does not actually resemble 

 any species of Aerxa is of course plain, but I certainly 

 regard the variety acheloia as a marked stage of incipient 

 mimicry. On the underside, the hindwing of this variety, 

 in its wet-season form, differs from that of the type in 

 having lost the whitish bands, which gives it a very marked 

 resemblance to Acnva serena-huxtoni. Again, the loss of 

 the discal row of spots on the upper side of the hindwing 

 points the same way, and it is interesting to note that, 

 so far as my experience in South-east Africa goes, where 

 A. serena-huxtoni occurs, there acheloia prevails over 

 the typical form. Again, the chief difference between 



